Torii session undefined - not injected in ember / firebase app

In an ember cli project using firebase, I've installed (using ember install) emberfire and torii. I have put the following configuration in my config/environment.js right after my firebase app url:

torii = {
  sessionServiceName: 'session',
}

And I've put an adapter into app/torii-adapters/application.js:

import Ember from 'ember';
import ToriiFirebaseAdapter from 'emberfire/torii-adapters/firebase';

export default ToriiFirebaseAdapter.extend({
  firebase: Ember.inject.service()
});

However, when I try to get torii's session variable on any route or controller:

this.get("session").fetch().catch(function() {});

the session is undefined:

Error while processing route: app Cannot read property 'fetch' of undefined TypeError: Cannot read property 'fetch' of undefined

I've followed the firebase docs/examples to the best of my knowledge, so I'm not sure what I'm missing. Is another step needed to have torii inject the session variable into all routes and controllers?

---

The versions in my stack are:

Ember-CLI: 1.13.7
Firebase (package.json): 2.2.9
EmberFire (package.json): 1.5.0
Torii (package.json): 0.5.1

NOTE: I currently have firebase itself working great—all of my models are in sync—so it is not likely the result of a faulty firebase setup. Also, this.get('session') returns undefined anywhere in any route or controller in my app.